Items are frequently despatched in matched groups in a common container. The items need to be packaged so that they will not be damaged in transit, and for such "matched group" items in particular often there is the complementary requirement that the items be kept spaced apart. This requirement of protection against damage whether arising from impacts "external" to the container or from self-impacts "internal" to the container applies particularly to the despatch of rigid items with sharp side edges, for instance matched pairs of hi-fi or stereo speakers.
It is known to single package sharp-edged units, spaced apart, using one of the oil-derived packaging materials; but these various materials are individually not highly favoured for one or more reasons i.e. since they may themselves be easily crushed by impacts they may only provide one-impact protection; they may not have the requisite impact strength and so may shear or fracture, again with only one fully effective impact-protection; they are expensive to make in small quantities, and in consequence are often only sold in substantial volumes, greater than that normally required by many manufacturers wishing to despatch their matching units in a single package or container; they are not generally available for just-in-time customers, but only with a long lead or order time.
An alternative packaging material which has been used is a length of L-section multi-layer corrugated paper ("L-pad"), placed back-to-back with a similar section; this material has the advantage that it can provide cushioned protection for square-cornered items, even after several impacts, and the advantage that it is strong in shear and so can be load bearing, for instance if the packages are stacked one on top of another during transit or in the warehouse. However, the material has traditionally been made from several layers of corrugated paper, so that when the L-sections are placed back-to-back the articles are often more widely spaced apart than desired, adding to packaging costs and container size. Also the placement of the sections back-to back and their retention in that condition whilst the items are being assembled in the container can require considerable skill.